Subcutaneous heparin injection is one of the most frequent nurses' clinical care. This study aimed to Identify and compare the effects of four different injection duration on pain and bruising associated with subcutaneous injection of heparin in 90 patients. Four injection methods were used for them:

A: 10s injections duration

B: 10s injection duration and waiting 10s before withdrawing the needle

C: 15s injection duration and waiting 5s before withdrawing the needle

D: 5s injection duration and waiting 15s before withdrawing the needle.

Bruising was measured by a flexible millimeter ruler 48h after each injection; and pain was measured by pain visual analogue scale immediately after the injection. Data will be analyzed by SPSS.

Inclusion Criteria:

• Inclination to participate in the study; filling out the form of conscious satisfaction
• Ability to answer the questions and determining the rate of pain
• Not being affected by blood clotting difficulties, tissue damages, injuries, and bruises in the site of injection.

Exclusion Criteria:

• Death,
• Discharge