Objective: To investigate the effect of cryotherapy application before versus after subcutaneous anticoagulant injection (SCAI) on pain intensity and hematoma formation.Methods: A quasi-experimental design was utilized.A convenient sample of 105 adult patients,who were admitted to one of the biggest teaching hospitals in Cairo and receiving SCAI,were recruited over a period of six months.Patients were randomly allocated into three groups: A Control group who received the routine hospital care (G1,n =35) and two intervention group who received cryotherapy for 5-min (G2: cryotherapy applied before SCAI,n=35;G3: cryotherapy applied after SCAI,n=35).Demographic and medical history data sheet,Pain Numeric Rating Scale and Hematoma Formation and Size Assessment Scale were used to collect the data.Results: The pain intensity among the patients in the two intervention groups (G2: Median =1.0;G3:Median =0) was significantly lower than in the control group (G1,Median =3.0).No significant difference was found between G2 and G3(P=0.728).Applying cryotherapy after SCAI (G3) decreased the frequency of hematoma formation (48hrs =31.4％ & 72hrs =28.5％) compared to applying it before injection (G2,100％) or not applying it (G1,100％).The size of hematoma in G3 was smaller than that in G2 (P ＜ 0.01).Conclusion: Applying cryotherapy significantly decreased pain intensity and hematoma occurrence/size.Applying cryotherapy after injection was more effective in preventing hematoma formation and decreasing its size than applying it before injection.