Currently we observe a huge number of publications, describing the role of glycine transporter GlyT1 inhibitors in schizophrenia treatment. The concept of application for these drugs derives from glutamatergic theory of schizophrenia. That theory explains psychotic disturbances as the consequence of NMDA receptor functioning defect. The role of mentioned receptor depends mostly on the presence of cofactors. One of such cofactors is the simplest amino acid, glycine. This amino acid affects the glycine-binding site, located on NR1 subunit of NMDAR and enables activation of the receptor. Substances enhancing the access of glycine to the receptor could improve neuroplasticity. Higher efficacy of these processes may protect from cognitive deterioration and negative symptoms in the course of schizophrenia. In this article we present a systematic review of current literature on the topic of GlyT1 in schizophrenia treatment. Firstly, we described the preclinical reasons for glycine enhancement use. Then we used CINAHL, EMBASE, EMCARE, Medline, PsycINFO, PubMed and Google Scholar databases, to extract and analyze evidence from clinical trials. GlyT1 inhibitors seem to have a potential in searching for novel substances in treatment of negative symptoms, but its capacity to reduce cognitive deficits is not evidenced. So far, clinical efficacy of several substances was proven, including N-methylglycine (sarcosine), bitopertin and derivatives obtained with chemical synthesis. Some of these substances are beneficial, but the number of published information in this area is not corresponding with the value of evidence.