Cytoplasmic streaming is the bulk flow of cytoplasm observed, not only in plants but also in animal oocytes and embryos. The flow of viscous fluid within the cytoplasm generates forces that re-arrange intracellular organelles, such as mitotic spindles and nuclei, to regulate cell growth, migration, and polarity. Cytoplasmic streaming is established by motor proteins and the viscoelastic cytoskeleton, including the actin filaments and microtubules. The mode of action can be changed in response to cell fate and developmental stage; however, its regulatory mechanism is unclear. The nematode Caenorhabditis elegans is a valuable model organism for analyzing cytoplasmic streaming because actin- and microtubule-dependent flows occur during oogenesis and embryogenesis, respectively. In this chapter, we describe methods for visualizing and quantitatively analyzing cytoplasmic streaming in C. elegans oocytes and embryos.