One bioequivalence study was carried out in healthy volunteers in order to compare the rate and extent of absorption of two oral formulations of quetiapine fumarate (CAS 111974-72-2) 25 mg film-coated tablet. Thirty subjects were administered quetiapine fumarate film-coated tablet of test and reference formulation in an open-label, randomised, fasting, two-period, two-sequence, crossover study. Blood samples were taken before and within 48 h after drug administration. Plasma concentrations were determined by LC/MS/MS. Log-transformed AUC and Cmax values were tested for bioequivalence based on the ratios of the geometric means (test/reference). Tmax was analysed nonparametrically. The 90% confidence intervals of the geometric mean values for the test/reference ratios for AUCo-t, and Cmax were within the bioequivalence acceptance range of 80-125%. It may be therefore concluded that the test formulation of quetiapine fumarate 25 mg film-coated tablet is bioequivalent to the reference product and can be prescribed interchangeably.