In the present work, 203 iron and steel industrial units located in and around Lahore were surveyed to gather information regarding physical parameters, processes involved, product types, raw materials used, fuel types, mode of employment, working conditions and use of PPEs in these units. General health and socio-economic status, disease history and anthropometric measurements of 656 workers from different work points were measured. Total serum proteins, albumin, ALT, AST and ALP were photometrically analyzed. Haematological parameters i.e., TLC, DLC, RBC, Hgb, Hct%, MCV, MCH, MCHC and platelet counts were made on automated haematology analyzer. Data was statistically analyzed on the basis of work points, job duration and worker’s age using ANOVA and students t-test at SPSS 13.0 version. Survey results revealed that the working conditions in these units are not satisfactory. Workers are exposed to variety of hazards. Socio-economic status of the workers also portrayed a dismal condition. Biochemical analysis showed general trend of increased concentration of total serum proteins, albumin and globulins, suggesting dehydration and non-specific infections as probable cause. Old workers working at comparatively higher temperature point showed more evident changes in total protein contents as compared to the young workers at the same points. ALT and AST, although within normal reference range, were evidently towards the higher limits in almost all categories of the workers. Younger and oldest workers with shortest and longest job duration presented higher value for ALT and AST as compared to the middle aged workers and with medium job duration. ALP is found significantly higher in all categories of workers depicting the obvious response to environmental stress. Physical activity along with the temperature appeared to be the contributory to enhance ALP activity. Although the haematological parameters did not show any direct correlation with the job duration or worker’s age but increased WBCs in circulation along with the complementary increase in lymphocytes number reflects the elicitation of immune response in these subjects. Hemoglobin, RBCs, Hct%, MCV, MCH, MCHC and platelets are found to show alteration, in general indicating a stress on the hematopoietic system to cope with the stress of hypoxic conditions and enhanced demand of energy due to heavy physical exertion. The results suggest that work point temperature along with heavy physical activity probably causes effects on liver physiology and also the hematopoietic system as apart of compensatory response. The results suggest more detailed studies with reference to heat stress and protein profile with special emphasis of the role of Hsps. Along with the detailed haematological investigations; studies on liver and kidney physiology are also recommended to understand the effect on hormones and electrolytes under hyperthermic conditions. Strict monitoring and enforcement of rules for the workers health and safety are strongly recommended.