The effectiveness of ritanserin, a selective 5-HT2 and 5-HT1c antagonist, in reducing negative symptoms in schizophrenia was investigated in a double-blind, placebo-controlled trial. Trial treatment was added to a stable neuroleptic treatment in 33 schizophrenic patients with predominantly negative symptoms. Ritanserin reduced the negative symptoms, as measured with the SANS. The main reduction was for the items facial expression, global affective flattening, and relationships with friends and peers. Also a reduction in total BPRS score was found, which approached statistical significance. Significant reductions were observed for the BPRS items emotional withdrawal and depressive mood. Ritanserin or other drugs blocking 5-HT2 and/or 5-HT1c receptors could be important in reducing specific symptoms in schizophrenic patients.