Online assessment is not new to teachers, students and educators worldwide as internet and personal computers have dominated the globe in late 20th and early 21st. centuries. Nonetheless, it was during COVID-19 pandemic that accelerated the development of online assessment as an alternative method to the traditional assessment. This study aims at investigating the forms of assessments as well as the effect(s) of online assessments on teaching practice amongst Vietnamese university teachers. Qualitative methodology is being used in this study. To collect the data, a sample of 10 teachers were chosen to get involved in the semi-structured interviews. The findings show that four main forms of assessments used by university teachers were formative, summative, self, and peer assessment. In addition, online assessments brought about both positive and negative effects for the teachers. While efficiency and time issue, technological issue, technological advancement, and teaching enhancement are the positive influences, teaching, classroom management and teacher-related issues are the negative ones. It is hoped that these results will make a contribution to the field of assessments in general.