This study investigated the effect of Ramadan on the haematological and steroid module of the Athletes Biological Passport (ABP) of the World Anti-Doping Agency (WADA). Nine healthy physically active subjects were tested in the morning and afternoon for two days before and three days during Ramadan. Sample collection and all analyses were performed according to WADA technical documents. Although there were significant changes in the haemoglobin concentration during Ramadan, especially during the first fasting week, none of the subjects in this study exceeded the individually calculated thresholds of the ABP. No significant effects on testosterone/epitestosterone (T/E) ratio were observed but only the afternoon specific gravity (SG) of the urine was elevated. Thus, when urinary steroid concentrations are required, SG corrections need to be performed. The haematological and the steroid module of the ABP can be reliably applied during Ramadan as the observed changes are only marginal.