Aim To establish median values for second trimester maternal serum human chorionic gonadotrophin (HCG) and alpha fetoprotein (AFP) at Aga Khan University Hospital- Nairobi (AKUH-N) using the Abbott Micro particle Enzyme immunoassay. Specific objectives •To perform measurements of second trimester maternal serum human chorionic gonadotrophin (HCG) and alpha fetoprotein (AFP) and to establish observed and regressed median values. •To establish regression coefficients for regressed medians of AFP and HCG. •To compare these data with data obtained from other geographical regions. Methodology 330 serum samples from women of gestational ages 15 to 20 weeks were analyzed for AFP and HCG. Observed medians were calculated for the raw data. Regressed medians were calculated by using a first-degree logarithmic–linear fit of the raw data. Results Regressed medians for maternal serum markers AFP (IU/ml), HCG (IU/ml) for our population can be estimated with the equation Y = 10(A+BX) where A and B are intercept and slope, and X= gestational age in decimal weeks. The regression coefficients (SE) for AFP are A=0.5858 and B=0.0653; for HCG, A=5.453 and B= -0.0612. The two regressions are highly significant (p 2=0.8924 for AFP and R2=0.7194 for HCG. A comparison of the AKUH-N regressed medians calculated in this study with those from other geographical population showed that the HCG and AFP medians compared very well with those from other countrieswith a p value of 0.3785 and 0.4831 respectively. Conclusions AKUH-N marker medians versus gestational time are found to show a pattern that is similar to that in the literature. The log–linear equation is observed to give a good fit and can be suggested as a tool for calculating Multiple of Medians values for Kenyan laboratories that use Abbott Micro particle Enzyme immunoassay technology.